Colorimetric resonant reflection biosensors have been fabricated on rigid surfaces, such as glass, using photoresist etch techniques. For example, a high refractive index dielectric thin film is deposited onto a glass substrate. A layer of photoresist is deposited over the dielectric thin film. The photoresist is exposed to light so as to selectively expose regions where the dielectric thin film is to be removed. The glass is immersed into a photoresist chemical developer solution that removes photoresist only from regions where the photoresist was exposed to higher intensity light. The glass substrate is exposed to an etchant (either a wet chemical solution or a dry reactive ion etch process) which removes the dielectric thin material from areas where the photoresist has been developed away. Any remaining photoresist is selectively removed. This glass substrate fabrication process is costly because each individual biosensor must undergo the expensive photolithography and etching procedures.
Another method of producing a colorimetric resonant reflection biosensor comprises spreading a thin layer of epoxy between a rigid “master” template that contains a negative of the desired colorimetric resonant reflection biosensor surface structure onto a flexible sheet of plastic substrate such as polycarbonate or polyester. The epoxy is cured and the plastic sheet with cured epoxy is peeled away from the master template. A high refractive index dielectric material is deposited over the structured plastic sheet. The limitation of the plastic substrate fabrication process is that the “cure and peel” procedure for generating a surface structure replicated within epoxy requires the substrate to be flexible in order to peel the cured structure away from the rigid master (typically implemented as a silicon or glass wafer or a metal film).
Methods of fabricating colorimetric resonant reflection biosensors that avoid expensive photolithography procedures or that do not require the use of flexible substrate materials are needed in the art.